Wireless communication method and wireless communication terminal for receiving data from plurality of wireless communication terminals

ABSTRACT

A wireless communication terminal communicating wirelessly with a base wireless communication terminal and unassociated with the base wireless communication terminal is disclosed. The wireless communication terminal includes: a transceiver; and a processor configured to receive, by using the transceiver, a multi-station Block ACK frame which indicates whether at least one of MAC frames transmitted from at least one of wireless communication terminals is received by using a first field of the multi-station Block ACK frame for indicating an association identifier corresponding to an association of each of the at least one of wireless communication terminals and the base wireless communication terminal, from the base wireless communication terminal, and determine whether a MAC frame transmitted from the wireless communication terminal is received by the base wireless communication terminal based on whether a second field of the multi-station Block ACK frame includes a MAC address of the wireless communication terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/KR2016/006488 filed on Jun. 17, 2016, which claims the priorityto Korean Patent Application No. 10-2015-0086022 filed in the KoreanIntellectual Property Office on Jun. 17, 2015, Korean Patent ApplicationNo. 10-2015-0098873 filed in the Korean Intellectual Property Office onJul. 13, 2015, and Korean Patent Application No. 10-2015-0122074 filedin the Korean Intellectual Property Office on Aug. 28, 2015, the entirecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wireless communication method and awireless communication terminal for increasing communication efficiencyby receiving data from a plurality of wireless communication terminals.

BACKGROUND ART

In recent years, with supply expansion of mobile apparatuses, a wirelesscommunication technology that can provide a rapid wireless Internetservice to the mobile apparatuses has been significantly spotlighted.The wireless communication technology allows mobile apparatusesincluding a smart phone, a smart pad, a laptop computer, a portablemultimedia player, an embedded apparatus, and the like to wirelesslyaccess the Internet in home or a company or a specific service providingarea.

One of most famous wireless communication technology is wireless LANtechnology. Institute of Electrical and Electronics Engineers (IEEE)802.11 has commercialized or developed various technological standardssince an initial wireless LAN technology is supported using frequenciesof 2.4 GHz. First, the IEEE 802.11b supports a communication speed of amaximum of 11 Mbps while using frequencies of a 2.4 GHz band. IEEE802.11a which is commercialized after the IEEE 802.11b uses frequenciesof not the 2.4 GHz band but a 5 GHz band to reduce an influence byinterference as compared with the frequencies of the 2.4 GHz band whichare significantly congested and improves the communication speed up to amaximum of 54 Mbps by using an Orthogonal Frequency DivisionMultiplexing (OFDM) technology. However, the IEEE 802.11a has adisadvantage in that a communication distance is shorter than the IEEE802.11b. In addition, IEEE 802.11g uses the frequencies of the 2.4 GHzband similarly to the IEEE 802.11b to implement the communication speedof a maximum of 54 Mbps and satisfies backward compatibility tosignificantly come into the spotlight and further, is superior to theIEEE 802.11a in terms of the communication distance.

Moreover, as a technology standard established to overcome a limitationof the communication speed which is pointed out as a weak point in awireless LAN, IEEE 802.11n has been provided. The IEEE 802.11n aims atincreasing the speed and reliability of a network and extending anoperating distance of a wireless network. In more detail, the IEEE802.11n supports a high throughput (HT) in which a data processing speedis a maximum of 540 Mbps or more and further, is based on a multipleinputs and multiple outputs (MIMO) technology in which multiple antennasare used at both sides of a transmitting unit and a receiving unit inorder to minimize a transmission error and optimize a data speed.Further, the standard can use a coding scheme that transmits multiplecopies which overlap with each other in order to increase datareliability.

As the supply of the wireless LAN is activated and further, applicationsusing the wireless LAN are diversified, the need for new wireless LANsystems for supporting a higher throughput (very high throughput (VHT))than the data processing speed supported by the IEEE 802.11n has comeinto the spotlight. Among them, IEEE 802.11ac supports a wide bandwidth(80 to 160 MHz) in the 5 GHz frequencies. The IEEE 802.11ac standard isdefined only in the 5 GHz band, but initial 11ac chipsets will supporteven operations in the 2.4 GHz band for the backward compatibility withthe existing 2.4 GHz band products. Theoretically, according to thestandard, wireless LAN speeds of multiple stations are enabled up to aminimum of 1 Gbps and a maximum single link speed is enabled up to aminimum of 500 Mbps. This is achieved by extending concepts of awireless interface accepted by 802.11n, such as a wider wirelessfrequency bandwidth (a maximum of 160 MHz), more MIMO spatial streams (amaximum of 8), multi-user MIMO, and high-density modulation (a maximumof 256 QAM). Further, as a scheme that transmits data by using a 60 GHzband instead of the existing 2.4 GHz/5 GHz, IEEE 802.11ad has beenprovided. The IEEE 802.11ad is a transmission standard that provides aspeed of a maximum of 7 Gbps by using a beamforming technology and issuitable for high bit rate moving picture streaming such as massive dataor non-compression HD video. However, since it is difficult for the 60GHz frequency band to pass through an obstacle, it is disadvantageous inthat the 60 GHz frequency band can be used only among devices in ashort-distance space.

Meanwhile, in recent years, as next-generation wireless communicationtechnology standards after the 802.11ac and 802.11ad, discussion forproviding a high-efficiency and high-performance wireless communicationtechnology in a high-density environment is continuously performed. Thatis, in a next-generation wireless communication technology environment,communication having high frequency efficiency needs to be providedindoors/outdoors under the presence of high-density terminals and baseterminals and various technologies for implementing the communicationare required.

Especially, as the number of devices using a wireless communicationtechnology increases, it is necessary to efficiently use a predeterminedchannel. Therefore, required is a technology capable of efficientlyusing bandwidths by simultaneously transmitting data between a pluralityof terminals and base terminals.

DISCLOSURE Technical Problem

An object of the present invention is to provide an efficient wirelesscommunication method and wireless communication terminal.

Especially, an object of the present invention is to provide a wirelesscommunication method and a wireless communication terminal for receivingdata from a plurality of wireless communication terminals.

Technical Solution

According to an embodiment of the present invention, a base wirelesscommunication terminal communicating with a wireless communicationterminal wirelessly which is unassociated with the base wirelesscommunication terminal, the base wireless communication terminalincludes: a transceiver; and a processor. The processor may beconfigured to receive, by using the transceiver, a MAC frame transmittedfrom the wireless communication terminal, insert an identifier for anunassociated wireless communication terminal and a MAC address of thewireless communication terminal respectively into a first field and asecond field of a multi-station Block ACK frame which indicates whetherat least one of MAC frames transmitted from at least one of wirelesscommunication terminals is received by using the first field ofmulti-station Block ACK frame for indicating an association identifiercorresponding to an association of each of the at least one of wirelesscommunication terminals and the base wireless communication terminal,and transmit the multi-station Block ACK frame. The identifier for anunassociated wireless communication terminal may not be allocatedthrough an association with the base wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal may be out of a range of a value that the associationidentifier is able to be allocated. The value of the identifier for anunassociated wireless communication terminal may be generated based onthe MAC address of the wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal may be a value pre-known to both the base wirelesscommunication terminal and the wireless communication terminal.

The processor may be configured to transmit a trigger frame triggeringrandom access, wherein the MAC frame transmitted from the wirelesscommunication terminal is transmitted in response to the trigger frame.

The trigger frame may signal a frequency band allocated for randomaccess by using a value of a specific association identifier, whereinthe MAC frame transmitted from the wireless communication terminal istransmitted through the frequency band allocated for random access.

The MAC frame transmitted from the wireless communication terminal maybe a management frame.

According to an embodiment of the present invention, a wirelesscommunication terminal communicating wirelessly with a base wirelesscommunication terminal and unassociated with the base wirelesscommunication terminal, the wireless communication terminal includes: atransceiver; and a processor. The processor may be configured toreceive, by using the transceiver, a multi-station Block ACK frame whichindicates whether at least one of MAC frames transmitted from at leastone of wireless communication terminals is received by using a firstfield of the multi-station Block ACK frame for indicating an associationidentifier corresponding to an association of each of the at least oneof wireless communication terminals and the base wireless communicationterminal, from the base wireless communication terminal, and determine,when the first field of the multi-station Block ACK frame includes anidentifier for an unassociated wireless communication terminal, whethera MAC frame transmitted from the wireless communication terminal isreceived by the base wireless communication terminal based on whether asecond field of the multi-station Block Ack frame includes a MAC addressof the wireless communication terminal. The identifier for anunassociated wireless communication terminal may not be allocatedthrough an association with the base wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal may be out of a range of a value that the associationidentifier is able to be allocated. The value of the identifier for anunassociated wireless communication terminal may be generated based onthe MAC address of the wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal may be a value pre-known to both the base wirelesscommunication terminal and the wireless communication terminal.

The processor may be configured to receive a trigger frame triggeringrandom access from the base wireless communication terminal, transmitthe MAC frame in response to the trigger frame, and determine whetherthe MAC frame transmitted in response to the trigger frame is receivedby the base wireless communication terminal based on the multi-stationBlock ACK frame.

The trigger frame may signal a frequency band allocated for randomaccess by using a value of a specific association identifier. Theprocessor may be configured to transmit the MAC frame through thefrequency band allocated for random access in response to the triggerframe.

The MAC frame transmitted in response to the trigger frame may be amanagement frame.

According to an embodiment of the present invention, an operation methodof a wireless communication terminal communicating with a base wirelesscommunication terminal wirelessly and unassociated with the basewireless communication terminal, the method includes: receiving amulti-station Block ACK frame which indicates whether at least one ofMAC frames transmitted from at least one of wireless communicationterminals is received by using a first field of the multi-station BlockACK frame for indicating an association identifier corresponding to anassociation of each of the at least one of wireless communicationterminals and the base wireless communication terminal, from the basewireless communication terminal, and determining, when the first fieldof the multi-station Block ACK frame includes an identifier for anunassociated wireless communication terminal, whether a MAC frametransmitted from the wireless communication terminal is received by thebase wireless communication terminal based on whether a second field ofthe multi-station Block ACK frame includes a MAC address of the wirelesscommunication terminal. The identifier for an unassociated wirelesscommunication terminal may not be allocated through an association withthe base wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal is out of a range of a value that the association identifier isable to be allocated. The value of the identifier for an unassociatedwireless communication terminal is generated based on the MAC address ofthe wireless communication terminal.

A value of the identifier for an unassociated wireless communicationterminal is a value pre-known to both the base wireless communicationterminal and the wireless communication terminal.

Advantageous Effects

An embodiment of the present invention is to provide an efficientwireless communication method and wireless communication terminal.

Especially, an embodiment of the present invention provides an efficientwireless communication method and wireless communication terminal in awireless communication environment in which a legacy wirelesscommunication terminal and a non-legacy wireless communication terminalcoexist.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a wireless LAN system according to anembodiment of the present invention.

FIG. 2 is a view illustrating a wireless LAN system according to anotherembodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a stationaccording to an embodiment of the inventive concept.

FIG. 4 is a block diagram illustrating a configuration of an accesspoint according to an embodiment of the present invention.

FIG. 5 is a view illustrating a process that a station sets an accesspoint and a link according to an embodiment of the present invention.

FIG. 6 shows a plurality of stations according to an embodiment of thepresent invention transmit an uplink MU PPDU to an access point based ona trigger frame.

FIG. 7 shows that a plurality of stations according to an embodiment ofthe present invention transmit an uplink MU PPDU to an access pointaccording to information on resource allocation indicated by a triggerframe.

FIG. 8 shows that a plurality of stations according to an embodiment ofthe present invention perform a random access based on a trigger frameand transmit an uplink MU PPDU to an access point.

FIG. 9 shows a specific format of a trigger frame according to anembodiment of the present invention.

FIG. 10 shows an index value indicating information on resourceallocation in a trigger frame according to an embodiment of the presentinvention.

FIG. 11 shows that a plurality of stations according to an embodiment ofthe present invention transmit buffer status information to an accesspoint in one TXOP, receive allocated resources from an access point, andtransmit an uplink MU PPDU.

FIG. 12 shows that a plurality of stations according to anotherembodiment of the present invention transmit buffer status informationto an access point in one TXOP, receive allocated resources from anaccess point, and transmit an uplink MU PPDU.

FIG. 13 shows that a plurality of stations continuously transmit uplinkMU PPDUs in one TXOP according to an embodiment of the presentinvention.

FIG. 14 shows that an access point according to an embodiment of thepresent invention transmits downlink MU PPDUs to a plurality of stationsand a plurality of stations transmit uplink MU PPDUs to an access pointin one TXOP.

FIG. 15 shows that a plurality of stations according to an embodiment ofthe present invention transmit an uplink MU PPDU to an access point, andan access point transmits downlink MU PPDUs to a plurality of stationsin one TXOP.

FIG. 16 shows a concrete format of a multi-wireless communicationterminal acknowledgment frame indicating whether or not a frametransmitted by a plurality of wireless communication terminals isreceived.

FIG. 17 shows the generation of an identifier for identifyingunassociated stations according to an embodiment of the presentinvention.

FIG. 18 shows whether or not an access point receives data transmittedby an unassociated station through a multi-wireless communicationterminal acknowledgment frame according to an embodiment of the presentinvention.

FIG. 19 shows a resource allocation method of a frequency band having abandwidth of 20 MHz according to an embodiment of the present invention.

FIG. 20 shows a signaling method using a leftover tone not used for datatransmission according to an embodiment of the present invention.

FIG. 21 shows a signaling method using a leftover tone according toanother embodiment of the present invention.

FIG. 22 shows an access point transmitting a management frame accordingto an embodiment of the present invention.

FIG. 23 shows that a station according to an embodiment of the presentinvention transmits a probe request frame to an access pointunassociated with a station based on a trigger frame.

FIG. 24 shows that a station according to an embodiment of the presentinvention transmits a management frame to an access point unassociatedwith a station based on a trigger frame.

FIG. 25 shows that an access point transmits a probe response frameafter receiving a probe request frame from a plurality of stationsaccording to an embodiment of the present invention.

FIG. 26 shows that an access point according to an embodiment of thepresent invention receives a probe request frame and a data frame from aplurality of stations, and then transmits an ACK frame for a proberesponse frame and a data frame together.

FIG. 27 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits a probe response frame through aprimary channel.

FIG. 28 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits the same probe response frame in 20MHz frequency bandwidth units.

FIG. 29 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits a probe response frame through theentire frequency band.

FIG. 30 is a flowchart illustrating operations of a first wirelesscommunication terminal and a second wireless communication terminalaccording to an embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. The presentinvention may, however, be embodied in different forms and should not beconstructed as limited to the embodiments set forth herein. Parts notrelating to description are omitted in the drawings in order to clearlydescribe the present invention and like reference numerals refer to likeelements throughout.

Furthermore, when it is described that one comprises (or includes orhas) some elements, it should be understood that it may comprise (orinclude or has) only those elements, or it may comprise (or include orhave) other elements as well as those elements if there is no specificlimitation.

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2015-0086022, Nos. 10-2015-00988732 and Nos.10-2105-0122074 filed in the Korean Intellectual Property Office and theembodiments and mentioned items described in the respective applicationsare included in the Detailed Description of the present application.

FIG. 1 is a diagram illustrating a wireless communication systemaccording to an embodiment of the present invention. For convenience ofdescription, an embodiment of the present invention is described throughthe wireless LAN system. The wireless LAN system includes one or morebasic service sets (BSS) and the BSS represents a set of apparatuseswhich are successfully synchronized with each other to communicate witheach other. In general, the BSS may be classified into an infrastructureBSS and an independent BSS (IBSS) and FIG. 1 illustrates theinfrastructure BSS between them.

As illustrated in FIG. 1, the infrastructure BSS (BSS1 and BSS2)includes one or more stations STA1, STA2, STA3, STA_d, and STA5, accesspoints PCP/AP-1 and PCP/AP-2 which are stations providing a distributionservice, and a distribution system (DS) connecting the multiple accesspoints PCP/AP-1 and PCP/AP-2.

The station (STA) is a predetermined device including medium accesscontrol (MAC) following a regulation of an IEEE 802.11 standard and aphysical layer interface for a wireless medium, and includes both anon-access point (non-AP) station and an access point (AP) in a broadsense. Further, in the present specification, a term ‘terminal’ may beused to refer to a concept including a wireless LAN communication devicesuch as non-AP STA, or an AP, or both terms. A station for wirelesscommunication includes a processor and a transceiver and according tothe embodiment, may further include a user interface unit and a displayunit. The processor may generate a frame to be transmitted through awireless network or process a frame received through the wirelessnetwork and besides, perform various processing for controlling thestation. In addition, the transceiver is functionally connected with theprocessor and transmits and receives frames through the wireless networkfor the station.

The access point (AP) is an entity that provides access to thedistribution system (DS) via wireless medium for the station associatedtherewith. In the infrastructure BSS, communication among non-APstations is, in principle, performed via the AP, but when a direct linkis configured, direct communication is enabled even among the non-APstations. Meanwhile, in the present invention, the AP is used as aconcept including a personal BSS coordination point (PCP) and mayinclude concepts including a centralized controller, a base station(BS), a node-B, a base transceiver system (BTS), and a site controllerin a broad sense.

A plurality of infrastructure BSSs may be connected with each otherthrough the distribution system (DS). In this case, a plurality of BSSsconnected through the distribution system is referred to as an extendedservice set (ESS).

FIG. 2 illustrates an independent BSS which is a wireless communicationsystem according to another embodiment of the present invention. Forconvenience of description, another embodiment of the present inventionis described through the wireless LAN system. In the embodiment of FIG.2, duplicative description of parts, which are the same as or correspondto the embodiment of FIG. 1, will be omitted.

Since a BSS3 illustrated in FIG. 2 is the independent BSS and does notinclude the AP, all stations STA6 and STA7 are not connected with theAP. The independent BSS is not permitted to access the distributionsystem and forms a self-contained network. In the independent BSS, therespective stations STA6 and STA7 may be directly connected with eachother.

FIG. 3 is a block diagram illustrating a configuration of a station 100according to an embodiment of the present invention.

As illustrated in FIG. 3, the station 100 according to the embodiment ofthe present invention may include a processor 110, a transceiver 120, auser interface unit 140, a display unit 150, and a memory 160.

First, the transceiver 120 transmits and receives a wireless signal suchas a wireless LAN packet, or the like and may be embedded in the station100 or provided as an exterior. According to the embodiment, thetransceiver 120 may include at least one transmit and receive moduleusing different frequency bands. For example, the transceiver 120 mayinclude transmit and receive modules having different frequency bandssuch as 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, thestation 100 may include a transmit and receive module using a frequencyband of 6 GHz or more and a transmit and receive module using afrequency band of 6 GHz or less. The respective transmit and receivemodules may perform wireless communication with the AP or an externalstation according to a wireless LAN standard of a frequency bandsupported by the corresponding transmit and receive module. Thetransceiver 120 may operate only one transmit and receive module at atime or simultaneously operate multiple transmit and receive modulestogether according to the performance and requirements of the station100. When the station 100 includes a plurality of transmit and receivemodules, each transmit and receive module may be implemented byindependent elements or a plurality of modules may be integrated intoone chip.

Next, the user interface unit 140 includes various types of input/outputmeans provided in the station 100. That is, the user interface unit 140may receive a user input by using various input means and the processor110 may control the station 100 based on the received user input.Further, the user interface unit 140 may perform output based on acommand of the processor 110 by using various output means.

Next, the display unit 150 outputs an image on a display screen. Thedisplay unit 150 may output various display objects such as contentsexecuted by the processor 110 or a user interface based on a controlcommand of the processor 110, and the like. Further, the memory 160stores a control program used in the station 100 and various resultingdata. The control program may include an access program required for thestation 100 to access the AP or the external station.

The processor 110 of the present invention may execute various commandsor programs and process data in the station 100. Further, the processor110 may control the respective units of the station 100 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 110 may execute the program foraccessing the AP stored in the memory 160 and receive a communicationconfiguration message transmitted by the AP. Further, the processor 110may read information on a priority condition of the station 100 includedin the communication configuration message and request the access to theAP based on the information on the priority condition of the station100. The processor 110 of the present invention may represent a maincontrol unit of the station 100 and according to the embodiment, theprocessor 110 may represent a control unit for individually controllingsome component of the station 100, for example, the transceiver 120, andthe like. The processor 110 may be a modem which modulates wirelesssignal transmitted to the transceiver 120 and demodulates wirelesssignal received from the transceiver 120, or modulator and/ordemodulator which modulates wireless signal transmitted to thetransceiver 120 and demodulates wireless signal received from thetransceiver 120. The processor 110 controls various operations ofwireless signal transmission/reception of the station 100 according tothe embodiment of the present invention. A detailed embodiment thereofwill be described below.

The station 100 illustrated in FIG. 3 is a block diagram according to anembodiment of the present invention, where separate blocks areillustrated as logically distinguished elements of the device.Accordingly, the elements of the device may be mounted in a single chipor multiple chips depending on design of the device. For example, theprocessor 110 and the transceiver 120 may be implemented while beingintegrated into a single chip or implemented as a separate chip.Further, in the embodiment of the present invention, some components ofthe station 100, for example, the user interface unit 140 and thedisplay unit 150 may be optionally provided in the station 100.

FIG. 4 is a block diagram illustrating a configuration of an AP 200according to an embodiment of the present invention.

As illustrated in FIG. 4, the AP 200 according to the embodiment of thepresent invention may include a processor 210, a transceiver 220, and amemory 260. In FIG. 4, among the components of the AP 200, duplicativedescription of parts which are the same as or correspond to thecomponents of the station 100 of FIG. 2 will be omitted.

Referring to FIG. 4, the AP 200 according to the present inventionincludes the transceiver 220 for operating the BSS in at least onefrequency band. As described in the embodiment of FIG. 3, thetransceiver 220 of the AP 200 may also include a plurality of transmitand receive modules using different frequency bands. That is, the AP 200according to the embodiment of the present invention may include two ormore transmit and receive modules among different frequency bands, forexample, 2.4 GHz, 5 GHz, and 60 GHz together. Preferably, the AP 200 mayinclude a transmit and receive module using a frequency band of 6 GHz ormore and a transmit and receive module using a frequency band of 6 GHzor less. The respective transmit and receive modules may performwireless communication with the station according to a wireless LANstandard of a frequency band supported by the corresponding transmit andreceive module. The transceiver 220 may operate only one transmit andreceive module at a time or simultaneously operate multiple transmit andreceive modules together according to the performance and requirementsof the AP 200.

Next, the memory 260 stores a control program used in the AP 200 andvarious resulting data. The control program may include an accessprogram for managing the access of the station. Further, the processor210 may control the respective units of the AP 200 and control datatransmission/reception among the units. According to the embodiment ofthe present invention, the processor 210 may execute the program foraccessing the station stored in the memory 260 and transmitcommunication configuration messages for one or more stations. In thiscase, the communication configuration messages may include informationabout access priority conditions of the respective stations. Further,the processor 210 performs an access configuration according to anaccess request of the station. The processor 210 may be a modem whichmodulates wireless signal transmitted to the transceiver 220 anddemodulates wireless signal received from the transceiver 220, ormodulator and/or demodulator which modulates wireless signal transmittedto the transceiver 220 and demodulates wireless signal received from thetransceiver 220. The processor 210 controls various operations such asradio signal transmission/reception of the AP 200 according to theembodiment of the present invention. A detailed embodiment thereof willbe described below.

FIG. 5 is a diagram schematically illustrating a process in which a STAsets a link with an AP.

Referring to FIG. 5, the link between the STA 100 and the AP 200 is setthrough three steps of scanning, authentication, and association in abroad way. First, the scanning step is a step in which the STA 100obtains access information of BSS operated by the AP 200. A method forperforming the scanning includes a passive scanning method in which theAP 200 obtains information by using a beacon message (S101) which isperiodically transmitted and an active scanning method in which the STA100 transmits a probe request to the AP (S103) and obtains accessinformation by receiving a probe response from the AP (S105).

The STA 100 that successfully receives wireless access information inthe scanning step performs the authentication step by transmitting anauthentication request (S107 a) and receiving an authentication responsefrom the AP 200 (S107 b). After the authentication step is performed,the STA 100 performs the association step by transmitting an associationrequest (S109 a) and receiving an association response from the AP 200(S109 b).

Meanwhile, an 802.1X based authentication step (S111) and an IP addressobtaining step (S113) through DHCP may be additionally performed. InFIG. 5, the authentication server 300 is a server that processes 802.1Xbased authentication with the STA 100 and may be present in physicalassociation with the AP 200 or present as a separate server.

When data is transmitted using Orthogonal Frequency Division Modulation(OFDMA) or Multi Input Multi Output (MIMO), any one wirelesscommunication terminal may transmit data to a plurality of wirelesscommunication terminals simultaneously. Also, any one wirelesscommunication terminal may simultaneously receive data from a pluralityof wireless communication terminals.

For convenience of description, any one wireless communication terminalthat communicates simultaneously with a plurality of wirelesscommunication terminals is referred to as a first wireless communicationterminal and a plurality of wireless communication terminals thatsimultaneously communicate with the first wireless communicationterminal are referred to as a plurality of second wireless communicationterminals. In addition, the first wireless communication terminal may bereferred to as a base wireless communication terminal (device). Inaddition, the first wireless communication terminal may be a wirelesscommunication terminal that allocates a communication medium resourceand performs scheduling in communication with a plurality of wirelesscommunication terminals. Specifically, the first wireless communicationterminal may perform the role of a cell coordinator. At this time, thefirst wireless communication terminal may be the access point 200. Inaddition, the second wireless communication terminal may be the station100 associated with the access point 200. In a specific embodiment, thefirst wireless communication terminal may be a wireless communicationterminal that allocates a communication medium resource and performsscheduling in an independent network, such as an ad-hoc network, whichis not connected to an external distribution service. In addition, thefirst wireless communication terminal may be at least one of a basestation, an eNB, and a transmission point TP.

Through FIGS. 6 to 31, an operation in which a plurality of secondwireless communication terminals transmit data and a first wirelesscommunication terminal receives data will be described. In particular,it is described that a first wireless communication terminal transmits atrigger frame, which is a MAC frame that triggers transmission of aplurality of second wireless communication terminals, and the pluralityof second wireless communication terminals transmit an uplink Multi-User(MU) PLCP Protocol Data Unit (PPDU) to the first wireless communicationterminal based on a trigger frame. At this time, the uplink MU PPDU is aPPDU that the plurality of second wireless communication terminalstransmit to the first wireless communication terminal. Also, a downlinkMU PPDU is a PPDU that the first wireless communication terminaltransmits to the plurality of second wireless communication terminals.The first wireless communication terminal may transmit the downlink MUPPDU to the plurality of second wireless communication terminals usingMU-MIMO or OFDMA. In addition, the plurality of second wirelesscommunication terminals may transmit the uplink MU PPDU to the firstwireless communication terminal using MU-MIMO or OFDMA.

FIG. 6 shows a plurality of stations according to an embodiment of thepresent invention transmit an uplink MU PPDU to an access point based ona trigger frame.

A first wireless communication terminal may trigger the transmission ofa plurality of second wireless communication terminals by transmitting atrigger frame. Specifically, when the first wireless communicationterminal transmits the trigger frame, the plurality of second wirelesscommunication terminals may transmit the uplink MU PPDU to the firstwireless communication terminal based on the trigger frame. At thistime, the plurality of second wireless communication terminals maytransmit the uplink MU PPDU to the first wireless communication terminalthrough OFDMA or MU-MIMO. Also, the uplink MU PPDU may include a dataframe, a management frame, and a buffer status report. The data framerepresents a MAC frame that includes data. The management framerepresents a MAC frame for communication operations. The buffer statusreport represents information on a status of a buffer for storing datato be transmitted by a wireless communication terminal.

The first wireless communication terminal may transmit a MAC frameindicating whether the uplink MU PPDU is received or not.

In the embodiment of FIG. 6, the access point AP transmits a triggerframe.

First to third stations STA1 to STA3 receiving the trigger frametransmit the uplink MU PPDU to the access point AP through OFDMA. Atthis time, the first to third stations STA1 to STA3 transmit the uplinkMU PPDU to the access point AP after a predetermined time xIFS from thereception of the trigger frame.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether the MAC frame included in the uplink MUPPDU transmitted from the first station STA1 to the third station STA3is received, to the first to third stations STA1 to STA3. At this time,the access point AP transmits a multi-station block ACK frame Multi-STABlock ACK after a predetermined time xIFS from the time when the uplinkMU PPDU is received from the first station STA1 to the third stationSTA3, to the first station STA1 to the third station STA3.

The first wireless communication terminal may transmit information onthe transmission scheduling of the second wireless communicationterminal to the plurality of second wireless communication terminalsthrough the trigger frame. The information on transmission schedulingmay include information on resource allocation. The information on theresource allocation may include information on a frequency bandallocated to the plurality of second wireless communication terminals bythe first wireless communication terminal. At this time, a unit of afrequency band used by the first wireless communication terminal and thesecond wireless communication terminal in the OFDMA communication may bereferred to as a resource unit (RU). Frequency band allocation throughthe trigger frame will be described in detail with reference to FIGS. 7and 8.

FIG. 7 shows that a plurality of stations according to an embodiment ofthe present invention transmit an uplink MU PPDU to an access pointaccording to information on resource allocation indicated by a triggerframe.

A first wireless communication terminal may assign a specific RU to aspecific second wireless communication terminal. At this time, thespecific second wireless communication terminal may be identified by atleast one of an association identifier for identifying the associationwith the first wireless communication terminal in the trigger frame, anaddress identifier for identifying the address of the second wirelesscommunication terminal, or a group identifier for identifying the groupto which the second wireless communication terminal belongs. In aspecific embodiment, the trigger frame may use a portion of anassociation identifier, an address identifier, or a group identifier. Inaddition, the trigger frame may be used by modifying an associationidentifier, an address identifier, or a group identifier. Theassociation identifier may be an AID defined in 802.11. In addition, thegroup identifier may be a GID defined in 802.11. In addition, theaddress identifier may be a MAC address defined in 802.11.

In the embodiment of FIG. 7, the access point AP transmits a triggerframe. The trigger frame Trigger indicates that an RU including 106tones is assigned to a station whose AID is 12. In addition, the triggerframe indicates that an RU including 26 tones is assigned to a stationwhose AID is 13. In addition, the trigger frame indicates that an RUincluding 106 tones is assigned to a station whose AID is 14.

The first to third stations STA1 to STA3 transmit the uplink MU PPDU tothe access point AP based on the trigger frame. Specifically, the firststation STA1 whose AID corresponds to 12 transmits the uplink MU PPDU tothe access point AP through the RU including 106 tones. In addition, thesecond station STA2 whose AID corresponds to 13 transmits the uplink MUPPDU to the access point AP through the RU including 26 tones. Inaddition, the third station STA3 whose AID corresponds to 14 transmitsthe uplink MU PPDU to the access point AP through the RU including 106tones. At this time, the first station STA1 to the third station STA3transmit the uplink MU PPDU to the access point AP after a predeterminedtime xIFS from the time when the trigger frame is received.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether the MAC frame included in the uplink MUPPDU transmitted from the first station STA1 to the third station STA3is received, to the first to third stations STA1 to STA3. At this time,the access point AP transmits a multi-station block ACK frame Multi-STABlock ACK after a predetermined time xIFS from the time when the uplinkMU PPDU is received from the first station STA1 to the third stationSTA3, to the first station STA1 to the third station STA3.

When the first wireless communication terminal assigns a specific RU toa specific second wireless communication terminal, the first wirelesscommunication terminal need to perform complicated process for resourceallocation. In addition, the first wireless communication terminal maygrasp all the communication conditions of the second wirelesscommunication terminal to perform efficient resource allocation. Inaddition, when the first wireless communication terminal assigns aspecific RU to a specific second wireless communication terminal, thefirst wireless communication terminal may not be able to receive theuplink MU PPDU from the second wireless communication terminalunassociated with the first wireless communication terminal. In order tosolve this problem, the first wireless communication terminal may allowrandom access to the plurality of second wireless communicationterminals. At this time, the trigger frame may indicate information onresource allocation for random access. This will be described in moredetail with reference to FIG. 8.

FIG. 8 shows that a plurality of stations according to an embodiment ofthe present invention perform a random access based on a trigger frameand transmit an uplink MU PPDU to an access point.

The trigger frame may indicate that a particular frequency band isallocated for random access. An associated second wireless communicationterminal as well as an unassociated second wireless communicationterminal may transmit an uplink MU PPDU over a frequency band allocatedfor random access. Also, the uplink MU PPDU may include a data frame, amanagement frame, and a Buffer Status Report (BSR) as described above.Accordingly, a plurality of second wireless communication terminals maymultiplex different types of MAC frames in the frequency domain usingOFDMA transmission and transmit the MAC frames to the first wirelesscommunication terminal. For example, the data frame transmission of oneof the second wireless communication terminals and the management frametransmission of another second wireless communication terminal may bemultiplexed in the frequency domain through OFDMA. Also, any one of thesecond wireless communication terminals may transmit the data frame andthe BSR to the first wireless communication terminal.

Accordingly, the plurality of second wireless communication terminalsmay transmit the BSR to the first wireless communication terminalthrough random access. Through this, the first wireless communicationterminal may fairly provide the plurality of second wirelesscommunication terminals an opportunity to transmit information on thebuffer status. The BSR transmission of the second wireless communicationterminal and the allocation of the frequency band to the plurality ofsecond wireless communication terminals by the first wirelesscommunication terminal based on the BSR will be described again withreference to FIGS. 11 and 12.

Additionally, the trigger frame may indicate a transmission condition ofthe second wireless communication terminal. The second wirelesscommunication terminal may transmit the uplink MU PPDU to the firstwireless communication terminal based on the transmission conditionindicated by the trigger frame. Specifically, the transmission conditionindicated by the trigger frame may include at least one of the length ofthe packet transmitted by the second wireless communication terminal,the transmission time, and the type of the response. At this time, thetype of the response may be the type of the MAC frame included in theuplink MU PPDU.

Also, the second wireless communication terminal may determine the sizeof the frequency band for transmitting the uplink MU PPDU. At this time,the second wireless communication terminal may determine the size of thefrequency band for transmitting the uplink MU PPDU in consideration ofthe transmission coverage. Specifically, the second wirelesscommunication terminal may select an RU having a small frequencybandwidth from among a plurality of RUs, and transmit the MU PPDUthrough the selected RU. In another specific embodiment, the secondwireless communication terminal may select the number of RUs that are totransmit the MU PPDU among the plurality of RUs. In another specificembodiment, the second wireless communication terminal may determine thesize of the frequency band based on the required transmission coverageof the second wireless communication terminal, within a frequency bandallocated for random access. For example, if the frequency bandwidth ofthe frequency band allocated for random access is 5 MHz and the size ofthe frequency bandwidth required for ensuring the required transmissioncoverage of the second wireless communication terminal is 2 MHz, thesecond wireless communication terminal may transmit the uplink MU PPDUwith a frequency bandwidth of 2 MHz within the frequency band allocatedfor the random access. Through such an operation, the second wirelesscommunication terminal may determine the transmission power density andtransmission coverage.

As described with FIGS. 7 and 8, a specific format of a trigger frameindicating a frequency band allocated to a plurality of second wirelesscommunication terminals will be described with reference to FIGS. 9 and10.

FIG. 9 shows a specific format of a trigger frame according to anembodiment of the present invention. FIG. 10 shows an index valueindicating information on resource allocation in a trigger frameaccording to an embodiment of the present invention.

As described above, the trigger frame may indicate a frequency bandallocated to the second wireless communication terminal. Specifically,the trigger frame may indicate a frequency band allocated to the secondwireless communication terminal through information indicating awireless communication terminal identifier that identifies the secondwireless communication terminal and a bandwidth of the frequency bandallocated to the second wireless communication terminal. At this time,the wireless communication terminal identifier may be AID. In a specificembodiment, the trigger frame may include information indicating awireless communication terminal identifier and a bandwidth of afrequency band corresponding to the wireless communication terminalidentifier. For example, the trigger frame may include an AIDcorresponding to a second wireless communication terminal that allocatesa frequency band and an index indicating a bandwidth of a frequency bandallocated to a second wireless communication terminal corresponding tothe AID. At this time, the position of a frequency band may be allocatedaccording to the AID order from the smallest frequency band used by thefirst wireless communication terminal. In addition, the index indicatingthe bandwidth of the frequency band allocated to the second wirelesscommunication terminal may be as shown in a table of FIG. 10(a).

In another specific embodiment, the trigger frame may includeinformation on a combination of a wireless communication terminalidentifier and an RU assigned by the first wireless communicationterminal to a plurality of second wireless communication terminals. Forexample, the trigger frame may include an index indicating a combinationof RUs to be allocated to a plurality of second wireless communicationterminals and an AID corresponding to the second wireless communicationterminal with an RU allocated. At this time, the index indicating thecombination of RUs to be allocated to the second wireless communicationterminal may be as shown in the table of FIG. 10(b).

Although it is described with reference to FIGS. 10(a) and 10(b) basedon a frequency band having a maximum of 242 tones, specific values ofFIGS. 10(a) and 10(b) where a frequency band having more tones than 242tones is used may be changed.

Also, the first wireless communication terminal may omit the frequencyband allocation information in the trigger frame. In the case where thefrequency band allocation information is omitted in the trigger frame,the trigger frame may indicate that the first wireless communicationterminal permits random access to the frequency band divided by apredetermined value. Through this embodiment, the size of the triggerframe may be reduced.

The trigger frame may indicate whether to permit only the transmissionof the designated second wireless communication terminal or whether topermit the random access of the second wireless communication terminal.Specifically, a frequency band allocated for random access may berepresented by a specific value of an association identifier. At thistime, the association identifier may be an AID. In addition, thespecific value of the association identifier indicating the frequencyband allocated for the random access may be a number other than 1 to2007 used as the association identifier. Specifically, the specificvalue of the association identifier indicating the frequency bandallocated for random access may be 0. Through this, the trigger framemay represent a frequency band for random access in the same format asallocating a frequency band to a specific second wireless communicationterminal, without additional information.

In addition, the trigger frame may include operating channel informationindicating information on a frequency band used by the first wirelesscommunication terminal. The operating channel information may include atleast one of information on a primary channel and information on acenter frequency. More specifically, the information on the primarychannel may be index information indicating the position of the primarychannel. In a specific embodiment, the second wireless communicationterminal unassociated with the first wireless communication terminal mayaccess the frequency band for uplink transmission through the operatingchannel information. At this time, the uplink transmission indicatesthat the second wireless communication terminal transmits the uplink MUPPDU to the first wireless communication terminal.

The trigger frame may include trigger type information indicating thetype of the trigger. In addition, the trigger frame may includeAllowable UL Type information indicating a type of a response to thetrigger. Specifically, the type of the response may include at least oneof a data frame, a management frame, and no limitation. In a specificembodiment, the allowed uplink type information may be represented bythe type and subtype information of a frame.

The trigger frame may include MCS information indicating information onthe MCS allowed to the second wireless communication terminal.Specifically, the MCS information may indicate the maximum value of theMCS that may be used by the trigger frame.

In the embodiment of FIG. 9, the trigger frame includes a Frame Controlfield indicating information on frame control, a Duration/ID fieldindicating information on the duration of the frame, an RA fieldindicating the address of a wireless communication terminal receivingthe trigger frame, a TA field indicating the address of a wirelesscommunication terminal transmitting the trigger frame, a Trigger Controlfield indicating information on the trigger control, and a TriggerInformation field indicating information on the trigger.

In the Frame Control field, the type field may represent a controlframe. Also, the subtype field may be a value specified for the triggerframe. Also, at least one of the More Fragment field and the More Datafield in the Frame control field may be used for additional informationtransmission.

The Duration/ID field may indicate the length of the uplink MU PPDUallowed by the trigger frame.

The Trigger Control field may include at least one of the trigger typeinformation, allowed uplink type information, operating channelinformation, and MCS information described above.

The Trigger Information field may include information on the combinationof the wireless communication terminal identifier described above andthe RUs assigned to the plurality of second wireless communicationterminals by the first wireless communication terminal.

The Transmit Opportunity (TXOP) represents a time section during which awireless communication terminal may use a wireless medium without aseparate contention procedure. The wireless communication terminal hasthe opportunity to obtain the TXOP through the contention procedure andto transmit the PPDU within the obtained TXOP. However, in order thatany one of the wireless communication terminals transmits a PPDU toanother wireless communication terminal, one of the wirelesscommunication terminals transmits another PPDU to another wirelesscommunication terminal, or another wireless communication terminaltransmits a PPDU to one of the wireless communication terminals, theTXOP must be acquired again through the contention procedure. Repetitionof such a contention procedure may impair transmission efficiency. Tosolve this problem, a plurality of MU PPDU transmissions within a TXOPmay be allowed through a trigger frame. This will be described withreference to FIGS. 11 to 15.

FIGS. 11 and 12 show that a plurality of stations according to anembodiment of the present invention transmit buffer status informationto an access point in one TXOP, receive allocated resources from anaccess point, and transmit a PPDU.

A plurality of second wireless communication terminals may continuouslytransmit the uplink MU PPDU to the first wireless communication terminalbased on the trigger frame in one TXOP. Specifically, in the TXOPobtained by the first wireless communication terminal through thecontention procedure, a plurality of second wireless communicationterminals may continuously transmit the uplink MU PPDU to the firstwireless communication terminal based on the trigger frame. At thistime, the first trigger frame may indicate a random access.Specifically, the second wireless communication terminal and the firstwireless communication terminal may operate as follows.

As described above, the plurality of second wireless communicationterminals may transmit the BSR to the first wireless communicationterminal through the random access. Through this, the first wirelesscommunication terminal may guarantee an opportunity to transmitinformation on the buffer status to the plurality of second wirelesscommunication terminals. The information on the buffer status may be aBSR.

At this time, the plurality of second wireless communication terminalsmay transmit the uplink MU PPDU including the BSR to the first wirelesscommunication terminal through the random access. Also, the uplink MUPPDU may include at least one of a data frame and a management frametogether with the BSR.

The first wireless communication terminal allocates transmissionscheduling to a plurality of second wireless communication terminalsbased on the received BSR. Through this, the first wirelesscommunication terminal may trigger the transmission of the secondwireless communication terminal in consideration of the buffer status ofthe second wireless communication terminal. Also, the first wirelesscommunication terminal transmits to the plurality of second wirelesscommunication terminals a MAC frame indicating whether or not the MACframe included in the uplink MU PPDU including the BSR is received.

The first wireless communication terminal transmits a trigger frameindicating transmission scheduling to a plurality of second wirelesscommunication terminals without an additional contention procedure.

The second wireless communication terminal transmits the uplink MU PPDUto the first wireless communication terminal based on the trigger frame.

The first wireless communication terminal transmits, to the plurality ofsecond wireless communication terminals, a MAC frame indicating whetheror not the MAC frame included in the uplink MU PPDU is received.

In the embodiment of FIG. 11, the access point AP transmits a triggerframe indicating random access. At this time, the access point APobtains the TXOP through the contention procedure and transmits thetrigger frame.

The first to third stations STA1 to STA3, the fifth station STA5, andthe seventh station STA7 transmit the uplink MU PPDU including the BSRto the access point AP.

The access point AP transmits a multi-station block ACK Multi-STA BlockACK indicating whether the MAC frame included in the uplink MU PPDU isreceived, to the first station STA1 to the third station STA3, the fifthstation STA5, and the seventh station STA7.

The access point AP allocates resources to each of the first stationSTA1 to the third station STA3, the fifth station STA5, and the seventhstation STA7 based on the BSR transmitted by the first to third stationsSTA1 to STA3, the fifth station STA5, and the seventh station STA7.Specifically, the access point AP allocates frequency bands for uplinkMU PPDU transmission to the first to third stations STA1 to STA3, thefifth station STA5, and the seventh station STA7.

The access point AP transmits a trigger frame indicating resourcesallocated to the first station STA1 to the third station STA3, the fifthstation STA5, and the seventh station STA7. The first to third stationsSTA1 to STA3, the fifth station STA5, and the seventh station STA7transmit the uplink MU PPDU to the access point AP based on the triggerframe. Specifically, the first to third stations STA1 to STA3, the fifthstation STA5, and the seventh station STA7 transmit the uplink MU PPDUto the access point AP based on the allocated resources.

The access point AP transmits a multi-station block ACK Multi-STA BlockACK indicating whether the MAC frame included in the uplink MU PPDU isreceived, to the first station STA1 to the third station STA3, the fifthstation STA5, and the seventh station STA7.

The first wireless communication terminal may not receive information onthe buffer status transmitted by the second wireless communicationterminal due to a transmission collision or the like. In such a case,the first wireless communication terminal allocates resources to theplurality of second wireless communication terminals based on thereceived information on the buffer status.

In the embodiment of FIG. 12, the access point AP does not receive theBSR transmitted by the seventh station STAT unlike the embodiment ofFIG. 11.

Accordingly, the access point AP allocates resources to each of thefirst station STA1 to the third station STA3 and the fifth station STA5based on the BSR transmitted from the first station STA1 to the thirdstation STA3 and the fifth station STA5. Specifically, the access pointAP allocates a frequency band for uplink MU PPDU transmission to thefirst station STA1 to the third station STA3 and the fifth station STA5.

The access point AP transmits a trigger frame indicating an allocatedresource to each of the first station STA1 to the third station STA3 andthe fifth station STA5.

The first STA1 to the third station STA3 and the fifth station STA5transmit the uplink MU PPDU to the access point AP based on the triggerframe. Specifically, the first STA1 to the third station STA3 and thefifth station STA5 transmit an uplink MU PPDU to an access point APbased on the allocated resources.

The access point AP transmits a multi-station block ACK Multi-STA BlockACK indicating whether the MAC frame included in the uplink MU PPDU isreceived, to the first station STA1 to the third station STA3 and thefifth station STA5.

FIG. 13 shows that a plurality of stations continuously transmit PPDUsin one TXOP according to an embodiment of the present invention.

As described with reference to FIGS. 11 and 12, a plurality of secondwireless communication terminals may continuously transmit the uplink MUPPDU to the first wireless communication terminal based on the triggerframe during one TXOP. In the case of FIGS. 11 and 12, the first triggerframe represents a random access. However, after transmitting the uplinkMU PPDU to the first wireless communication terminal, a plurality ofsecond wireless communication terminals may transmit the uplink MU PPDUto the first wireless communication terminal again in one TXOP based ona trigger frame for allocating resources to a specific second wirelesscommunication terminal.

In the embodiment of FIG. 13, the access point AP transmits a triggerframe that allocates resources, to a specific station. At this time, theaccess point AP may obtain the TXOP through the contention procedure andtransmit the trigger frame.

The plurality of stations transmit the uplink MU PPDU including the dataframe to the access point AP based on the trigger frame.

The access point AP transmits a multi-station block ACK Multi-STA BlockACK indicating whether or not the MAC frame included in the uplink MUPPDU transmitted by the plurality of stations is received, to the accesspoint AP.

The access point AP transmits a trigger frame indicating a random accesswithout a separate contention procedure.

The plurality of stations transmit the uplink MU PPDU to the accesspoint AP based on the trigger frame. At this time, the uplink MU PPDUmay include at least one of buffer status information, a data frame, anda management frame. Accordingly, a plurality of stations may multiplexdifferent types of MAC frames in the frequency domain and transmit theMAC frames to an access point AP, through OFDMA transmission. Forexample, the data frame transmission of one station and the managementframe transmission of another station may be multiplexed in thefrequency domain through OFDMA. Also, any one of the stations maytransmit a data frame and a BSR to an access point AP.

The access point AP transmits a multi-station block ACK Multi-STA BlockACK indicating whether or not the MAC frame included in the uplink MUPPDU transmitted by the plurality of stations is received, to the accesspoint AP.

It is described with reference to FIGS. 11 to 13 that the plurality ofsecond wireless communication terminals continuously transmit the uplinkMU PPDU to the first wireless communication terminal based on thetrigger frame during one TXOP. A plurality of second wirelesscommunication terminals and a first wireless communication terminal mayalternately transmit MU PPDUs based on a trigger frame in one TXOP. Thiswill be described with reference to FIGS. 14 and 15.

FIG. 14 shows that an access point according to an embodiment of thepresent invention transmits uplink MU PPDUs to a plurality of stationsand a plurality of stations transmit downlink PPDUs to an access pointin one TXOP.

In one TXOP, after the first wireless communication terminal transmitsthe downlink MU PPDU to the plurality of second wireless communicationterminals, the plurality of second wireless communication terminals maytransmit the uplink MU PPDU to the first wireless communicationterminal. Specifically, a plurality of second wireless communicationterminals may transmit an uplink MU PPDU to a first wirelesscommunication terminal in the TXOP obtained by the first wirelesscommunication terminal to transmit the downlink MU PPDU through thecontention procedure. At this time, the first wireless communicationterminal may transmit the trigger frame to the plurality of secondwireless communication terminals, and the plurality of second wirelesscommunication terminals may transmit the uplink MU PPDU to the firstwireless communication terminal based on the trigger frame. In aspecific embodiment, the trigger frame may represent a random access.Also, the uplink MU PPDU may include at least one of information on abuffer status, a data frame, and a management frame. Accordingly, aplurality of second wireless communication terminals may multiplexdifferent types of MAC frames in the frequency domain using OFDMAtransmission and transmit the MAC frames to the first wirelesscommunication terminal. For example, the data frame transmission of oneof the second wireless communication terminals and the management frametransmission of another second wireless communication terminal may bemultiplexed in the frequency domain through OFDMA. Also, any one of thesecond wireless communication terminals may transmit the data frame andthe BSR to the first wireless communication terminal.

Also, in a specific embodiment, the first wireless communicationterminal may transmit the trigger frame together while transmitting thedownlink MU PPDU including the data frame. Through this, the firstwireless communication terminal may reduce the time required fortransmission to the PPDU.

In the embodiment of FIG. 14, an access point AP transmits downlink MUPPDUs to a plurality of stations. The access point AP acquires the TXOPthrough a contention procedure and transmits the downlink MU PPDU to aplurality of stations.

The plurality of stations transmit an ACK frame for downlink MU PPDUtransmission to the access point AP. At this time, a plurality ofstations may transmit an ACK frame for downlink MU PPDU transmissionusing OFDMA.

The access point AP transmits a trigger frame indicating a random accesswithout a separate contention procedure.

The plurality of stations transmit the uplink MU PPDU to the accesspoint AP based on the trigger frame. At this time, the uplink MU PPDUmay include at least one of buffer status information, a data frame, anda management frame. Accordingly, a plurality of stations may multiplexdifferent types of MAC frames in the frequency domain and transmit themto an access point AP, through OFDMA transmission. For example, the dataframe transmission of one station and the management frame transmissionof another station may be multiplexed in the frequency domain throughOFDMA. Also, any one of the stations may transmit a data frame and a BSRto an access point AP.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether or not the MAC frame included in the uplinkMU PPDU transmitted by the plurality of stations is received, to theaccess point AP.

FIG. 15 shows that a plurality of stations according to an embodiment ofthe present invention transmit an uplink MU PPDU to an access point, andan access point transmits downlink MU PPDUs to a plurality of stationsin one TXOP.

In one TXOP, a plurality of second wireless communication terminals maytransmit uplink MU PPDUs to a first wireless communication terminal anda first wireless communication terminal may transmit downlink MU PPDUsto a plurality of second wireless communication terminals. Specifically,the first wireless communication terminal may acquire the TXOP throughthe contention procedure to transmit the trigger frame, and theplurality of second wireless communication terminals may transmit theuplink MU PPDU based on the trigger frame. At this time, in the sameTXOP, the first wireless communication terminal may transmit thedownlink MU PPDU to a plurality of second wireless communicationterminals without a separate contention procedure.

At this time, the first wireless communication terminal transmits to theplurality of second wireless communication terminals an ACK frameindicating whether a MAC frame included in a down link MU PPDU includinga data frame and an uplink MU PPDU transmitted by the plurality ofsecond wireless communication terminals is received together.

In the embodiment of FIG. 15, the access point AP transmits a triggerframe indicating random access.

The plurality of stations transmit the uplink MU PPDU to the accesspoint AP based on the trigger frame. At this time, the uplink MU PPDUmay include at least one of buffer status information, a data frame, anda management frame. Accordingly, a plurality of stations may multiplexdifferent types of MAC frames in the frequency domain and transmit theMAC frames to an access point AP, through OFDMA transmission. Forexample, the data frame transmission of one station and the managementframe transmission of another station may be multiplexed in thefrequency domain through OFDMA. Also, any one of the stations maytransmit a data frame and a BSR to an access point AP.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether or not the MAC frame included in the uplinkMU PPDU transmitted by the plurality of stations is received, to theaccess point (AP).

The AP transmits downlink MU PPDUs to a plurality of stations without aseparate contention procedure.

The plurality of stations transmit an ACK frame for downlink MU PPDUtransmission to the AP. At this time, a plurality of stations maytransmit an ACK frame for downlink MU PPDU transmission using OFDMA.

As described above, when a plurality of second wireless communicationterminals transmit the uplink MU PPDU to the first wirelesscommunication terminal, the first wireless communication terminal maytransmit ACK for the MAC frame included in the uplink MU PPDUtransmitted by the second wireless communication terminal. At this time,the ACK frame may be referred to as a multi-station block ACK frameMulti-STA Block ACK. A specific format of the multi-station block ACKframe will be described with reference to FIGS. 16 to 18.

FIG. 16 shows a concrete format of a multi-wireless communicationterminal acknowledgment frame indicating whether or not a frametransmitted by a plurality of wireless communication terminals isreceived.

The multi-station block ACK frame may indicate whether or not the MACframe transmitted by each of the plurality of stations is received.Specifically, the multi-station block ACK frame may indicate whether ornot to receive the Traffic Identifier (TID) of a MAC frame transmittedby each of a plurality of wireless communication terminals. In addition,the multi-station block ACK frame may indicate whether all the MACframes included in the MU PPDUs transmitted by the plurality of wirelesscommunication terminals are received.

In addition, the multi-station block ACK frame may identify each of aplurality of wireless communication terminals through an associationidentifier. At this time, the association identifier may be an AID or apartial AID.

The specific format of the multi-station block ACK frame may be amodification of the format of the multi-TID Block ACK frame of the802.11 standard.

In a multi-station block ACK frame, the Per TID Info field may includethe AID or partial AID of the wireless communication terminal. In aspecific embodiment, the field indicating the AID or the partial AID ofthe wireless communication terminal may be an 11-bit field. In addition,the Per TID Info field may include a field indicating whether all theMAC frames transmitted by the wireless communication terminal arereceived or not. If the Per TID Info field indicates whether all the MACframes included in the MU PPDU transmitted by the wireless communicationterminal are received, the Block Ack Starting Sequence Control field andthe Block Ack Bitmap field may be omitted. In a specific embodiment, thefield indicating whether all the MAC frames transmitted by the wirelesscommunication terminal are received may be a 1-bit field.

As described above, the second wireless communication terminalunassociated with the first wireless communication terminal may alsotransmit the uplink MU PPDU based on the trigger frame. When a secondwireless communication terminal unassociated with the first wirelesscommunication terminal transmits an uplink MU PPDU based on a triggerframe, there is a problem that the first wireless communication terminalindicates a second wireless communication terminal unassociated with thefirst wireless communication terminal in the multi-station block ACKframe. This will be described with reference to FIGS. 17 and 18.

FIG. 17 shows the generation of an identifier for identifyingunassociated stations according to an embodiment of the presentinvention.

The first wireless communication terminal may use a specific value asthe AID of the second wireless communication terminal unassociated withthe first wireless communication terminal in order to identify thesecond wireless communication terminal unassociated with the firstwireless communication terminal. Specifically, the first wirelesscommunication terminal may use a specific value in the multi-stationblock ACK frame as the AID of the second wireless communication terminalunassociated with the first wireless communication terminal. At thistime, the specific value may be a value not assigned by association withthe first wireless communication terminal. In addition, the particularvalue may be referred to as a temporary AID or a temporary partial AID.In addition, the temporary AID may be included in the Per TID Info ofthe multi-station block ACK frame described above.

The first wireless communication terminal may designate the value of thetemporary AID with a value outside the range that the AID is able to beallocated. Specifically, the first wireless communication terminal maydesignate the value of the temporary AID with a number other than 1 to2007. Further, the first wireless communication terminal may designatethe value of the temporary AID based on the identifier of the secondwireless communication terminal. At this time, the identifier of thesecond wireless communication terminal may be the MAC address of thesecond wireless communication terminal. In addition, the identifier ofthe second wireless communication terminal may be an identifier of thesecond wireless communication terminal used by the second wirelesscommunication terminal when transmitting the uplink MU PPDU.Furthermore, the identifier of the second wireless communicationterminal may be a value pre-known to both the first wirelesscommunication terminal and the second wireless communication terminal.

Specifically, the first wireless communication terminal may designate atemporary AID value based on the following equation.Temporary AID=ID of STA % 40+2008

At this time, the ID of STA indicates the identifier of the secondwireless communication terminal. As described above, the identifier ofthe second wireless communication terminal may be one of the MAC addressof the second wireless communication terminal, the identifier of thesecond wireless communication terminal used by the second wirelesscommunication terminal when transmitting the uplink MU PPDU, and a valuepre-known to both the first wireless communication terminal and thesecond wireless communication terminal.

In another specific embodiment, the Block ACK Bitmap of themulti-station block ACK frame described with reference to FIG. 16 mayinclude the identifier of the second wireless communication terminal. Atthis time, the Block ACK Bitmap field of the Block ACK frame mayindicate that all the MAC frames included in the MU PPDU transmitted bythe second wireless communication terminal corresponding to the MACaddress are received. At this time, the BA info field may indicate thatthe Block ACK Bitmap field includes the MAC address. In addition, themulti-station block ACK frame may include a temporary AID in the Per TIDInfo field and a MAC address value in the Block ACK Bitmap field. Atthis time, the second wireless communication terminal may determinewhether the temporary AID value indicates the second wirelesscommunication terminal through the Block Ack Bitmap field.

FIG. 18 shows whether or not an access point receives data transmittedby an unassociated station through a multi-wireless communicationterminal acknowledgment frame according to an embodiment of the presentinvention.

The first wireless communication terminal may transmit the trigger frameindicating the resource allocated to the specific second wirelesscommunication terminal and the resource allocated to the random access.

At this time, the trigger frame may signal the resource allocated to thespecific second wireless communication terminal through the associationidentifier of the specific second wireless communication terminal.

In addition, the trigger frame may signal resources allocated to arandom access through an AID value representing a random access. The AIDvalue representing the random access may be 0 as described above.

The plurality of second wireless communication terminals transmit theuplink MU PPDU to the first wireless communication terminal based on thetrigger frame. Specifically, a specific second wireless communicationterminal that receives allocated resources through the trigger frametransmits the uplink MU PPDU to the first wireless communicationterminal through the allocated resources. In addition, the secondwireless communication terminal that does not receive a resource throughthe trigger frame transmits the uplink MU PPDU through the resourcesallocated to the random access. At this time, the second wirelesscommunication terminal unassociated with the first wirelesscommunication terminal may also transmit the uplink MU PPDU through theresources allocated to the random access.

The first wireless communication terminal transmits a multi-stationblock ACK frame similar to the embodiment described with reference toFIGS. 16 and 17. Specifically, whether the MAC frame included in theuplink MU PPDU transmitted by the second wireless communication terminalunassociated with the first wireless communication terminal is receivedmay be signaled through the temporary AID.

In the embodiment of FIG. 18, an access point AP transmits a triggerframe that allocates resources to a specific station and allocatesresources for a random access at the same time. Specifically, thetrigger frame indicates that two 106-tone RUs are assigned to stationswith an AID of 12 and an AID of 14, respectively, and 26-tone RUs areassigned to random access.

The first station STA1 corresponding to an AID 12 transmits the uplinkMU PPDU to the access point AP through the 106-tone RU. The thirdstation STA3 corresponding to an AID 14 transmits the uplink MU PPDU tothe access point AP through the 106-tone RU.

The second station STA2 unassociated with the access point transmits theuplink MU PPDU to the access point AP through the 26-tone RU.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether the MAC frame included in the uplink MUPPDU transmitted from the first station STA1 to the third station STA3is received, to the first to third stations STA1 to STA3. At this time,the multi-station block ACK frame Multi-STA Block ACK indicates whetheror not the MAC frame included in the uplink MU PPDU transmitted by thefirst station STA1 is received through the AID value 12. In addition,the multi-station block ACK frame Multi-STA Block ACK indicates whetheror not the MAC frame included in the uplink MU PPDU transmitted by thethird station STA3 is received through the AID value 14. In addition,the multi-station block ACK frame Multi-STA Block ACK indicates whetheror not the MAC frame included in the uplink MU PPDU transmitted by thethird station STA3 is received through the temporary AID.

FIG. 19 shows a resource allocation method of a frequency band having abandwidth of 20 MHz according to an embodiment of the present invention.

In OFDM transmission, a plurality of subcarriers transmitted in thefrequency band transmit data. In OFDMA transmission, a plurality ofsub-frequency bands included in a frequency band are allocated to aplurality of wireless communication terminals, respectively. At thistime, a plurality of subcarriers respectively corresponding to theplurality of sub-frequency bands transmit data for the plurality ofrespective wireless communication terminals. At this time, thesubcarrier may be referred to as a tone.

Specifically, the first wireless communication terminal may allocate afrequency band to the second wireless communication terminal using atleast one of 26 tones, 52 tones, 106 tones, and 242 tones in a frequencyband having a bandwidth of 20 MHz.

Specifically, when a wireless communication terminal performs OFDMtransmission in a frequency band having a bandwidth of 20 MHz, thewireless communication terminal may transmit data through 242 tones. Atthis time, the wireless communication terminal may use 11 guard tonesand 3 DC tones.

Also, the wireless communication terminal may use a combination of 26tones, 52 tones, and 106 tones. At this time, the wireless communicationterminal may use 11 guard tones and 7 DC tones. Specifically, thewireless communication terminal may use six 26 tones. Also, the wirelesscommunication terminal may use three 26 tones and three 52 tones.Further, the wireless communication terminal may use two 52 tones, one26 tones, and one 106 tones. Further, the wireless communicationterminal may use one 26 tones and two 106 tones.

Also, the wireless communication terminal may use a combination of 26tones and 52 tones. At this time, four leftover tones are generated. Theleftover tone indicates subcarriers that are not used for datatransmission to a specific wireless communication terminal inconsideration of transmission efficiency, according to the sub-frequencyband allocation method. A method of utilizing the leftover tone will bedescribed with reference to FIGS. 20 to 22.

FIGS. 20 and 21 show a signaling method using a leftover tone not usedfor data transmission according to an embodiment of the presentinvention.

The first wireless communication terminal may indicate a frequency bandin which the management frame is located through leftover tones.Specifically, a plurality of leftover tones may indicate an index of anRU where a management frame is located. When a first wirelesscommunication terminal modulates a signal through BPSK, each of aplurality of leftover tones indicates a value of 0 or 1 according towhether a leftover tone transmits a signal, and the combination of thevalues represented by the leftover tones may signal the position of themanagement frame. Depending on the modulation method used by the firstwireless communication terminal, the range of values that leftover tonesare able to represent may vary.

At this time, if the value of the leftover tone is not null, the secondwireless communication terminal may recognize that the management frameis transmitted. Also, the second wireless communication terminal maydecode the left overtones to acquire information on the frequency bandin which the management frame is located. Also, the second wirelesscommunication terminal may recognize the transmission format of the MACframe in an RU other than RUs in which the management frame istransmitted, using the AID or GID value specified in the HE-SIG field.For example, the second wireless communication terminal may use the AIDor GID value specified in the HE-SIG field to recognize which one of aplurality of RUs is utilized for transmission of an MAC frame.

In the embodiment of FIG. 20(a), the four leftover tones have values of0, 0, 1, and 1, respectively. At this time, the leftover tone indicatesthat a probe response frame, which is a kind of management frame similarto 20(b), is located in the frequency band whose RU index valuecorresponds to 3.

In another specific embodiment, the first wireless communicationterminal may signal information on the management frame through acombination of the number and position of leftover tones. Specifically,the first wireless communication terminal may signal information on themanagement frame through a combination of the number and position ofleftover tones. At this time, the leftover tone may be locatedsymmetrically. This is to reduce the PAPR.

In the embodiment of FIG. 21, the leftover tone may be located at eachof six positions as shown in FIG. 21(a). At this time, when the leftovertones are symmetrically located, the combination of the positions andthe numbers of the leftover tones is a total of six as shown in FIG.21(b). Therefore, the leftover tone may signal the positions of sixdifferent types of management frames. At this time, the position of themanagement frame signaled by the leftover tone may be the index value ofthe RU where the management frame is located.

FIG. 22 shows an access point transmitting a management frame accordingto an embodiment of the present invention.

The first wireless communication terminal may transmit the managementframe while transmitting the data frame. Specifically, the firstwireless communication terminal may transmit the data frame and themanagement frame together through OFDMA. Specifically, the firstwireless communication terminal may transmit a management frame throughthe remaining resource after allocating a resource to the secondwireless communication terminal that is to transmit the downlink MU PPDUduring OFDMA. Also, the first wireless communication management framemay be transmitted aperiodically. At this time, the first wirelesscommunication terminal may signal the position of the management framesimilar to the embodiment described with reference to FIGS. 20 and 21.

In a specific embodiment, the management frame may represent a broadcastframe. Specifically, the management frame may represent at least one ofa beacon frame and a probe response frame.

In the embodiment of FIG. 22, the access point AP periodically transmitsa beacon frame. At this time, the access point AP transmits the beaconframe together aperiodically while transmitting the data frame to theplurality of stations. In addition, the access point AP transmits aprobe response frame while transmitting a data frame to a plurality ofstations.

Through such an operation, the first wireless communication terminal mayreduce the number of contention procedures for transmitting themanagement frame. Accordingly, the second wireless communicationterminal may quickly scan the first wireless communication terminal andbe associated with the first wireless communication terminal.Specifically, in a situation where many wireless communication terminalsexist in a narrow area, the second wireless communication terminal mayscan the first wireless communication terminal and reduce the timeassociated with the first wireless communication terminal.

As described above, when a plurality of second wireless communicationterminals use OFDMA, the plurality of second wireless communicationterminals may transmit the management frame and the data frame togetherto the first wireless communication terminal. This will be described indetail with reference to FIGS. 23 to 29.

FIG. 23 shows that a station according to an embodiment of the presentinvention transmits a probe request frame to an access pointunassociated with a station based on a trigger frame.

In general, when the second wireless communication terminal receives aprobe response frame within Min Probe Response Time from the time whentransmitting the probe request frame, the second wireless communicationterminal waits Max Probe Response Time from the time when transmittingthe probe request frame. When Max Probe Response Time elapses from thetime when the probe request frame is transmitted, the second wirelesscommunication terminal processes all the received probe response frames.The second wireless communication terminal associates with the firstwireless communication terminal based on the probe response framereceived first through this operation to prevent the case where thewireless communication terminal is not be associated with the optimalfirst wireless communication terminal.

However, when the second wireless communication terminal transmits theprobe request based on the trigger frame, the second wirelesscommunication terminal specifies the first wireless communicationterminal and transmits the probe request. Therefore, the second wirelesscommunication terminal may process the probe response frame within atime shorter than Max Probe Response Time from the time when the proberesponse frame is received. For example, the second wirelesscommunication terminal may process the probe response frame as soon asit receives the probe response frame.

In the embodiment of FIG. 23, the second station transmits a proberequest frame to the access point AP based on the trigger frame.Specifically, the second station transmits a probe request frame to theaccess point AP through the 26-tone RU allocated for the random accessindicated by the trigger frame.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether the MAC frame included in the uplink MUPPDU transmitted from the first station STA1 and the third station STA3is received, to the first and third stations STA1 to STA3.

Then, the access point AP transmits a probe response frame to the secondstation STA2.

The second station STA2 transmits an ACK frame for the probe responseframe to the access point AP within a time shorter than Max ProbeResponse Time.

FIG. 24 shows that a station according to an embodiment of the presentinvention transmits a management frame to an access point unassociatedwith a station based on a trigger frame.

When a plurality of second wireless communication terminals transmit adata frame and a management frame together to the first wirelesscommunication terminal, the first wireless communication terminaltransmits an ACK frame for data frame transmission and transmits aresponse to the management frame. Therefore, when the plurality ofsecond wireless communication terminals transmit the data frame and themanagement frame together to the first wireless communication terminal,the time when the second wireless communication terminal receives theresponse to the management frame may be slower than the case where thesecond wireless communication terminal alone transmits the managementframe.

Therefore, when the plurality of second wireless communication terminalstransmit the data frame and the management frame together to the firstwireless communication terminal, the second wireless communicationterminal may wait the response to the management frame for a time longerthan the response time for a general management frame.

As described with reference to FIGS. 23 and 24, when the plurality ofsecond wireless communication terminals transmit the data frame and themanagement frame together to the first wireless communication terminal,the time when the second wireless communication terminal receives theresponse to the management frame may be slower than the case where thesecond wireless communication terminal alone transmits the managementframe. Therefore, there is a need for a method through which the secondwireless communication terminal may quickly receive a response to themanagement frame. This will be described with reference to FIGS. 25 and26.

FIG. 25 shows that an access point transmits a probe response frameafter receiving a probe request frame from a plurality of stationsaccording to an embodiment of the present invention.

When the first wireless communication terminal and the plurality ofsecond wireless communication terminals transmit a data frame and amanagement frame together and the first wireless communication terminalfails to receive a data frame transmitted by the second wirelesscommunication terminal due to a transmission collision or the like, thefirst wireless communication terminal may transmit a response to themanagement frame without transmitting the ACK frame for the data frame.

In the embodiment of FIG. 25, an access point AP transmits a triggerframe indicating a resource allocation for a random access.

The first station STA1 to the third station STA3 and the fifth stationSTA5 transmit the probe request frame to the access point AP based onthe trigger frame.

The seventh station STA7 transmits the data frame to the access point APbased on the trigger frame. However, due to a transmission collision,the access point AP does not receive the data frame transmitted by theseventh station STA7.

The access point AP transmits the probe response frame to the firststation STA1 to the third station STA3, and the fifth station STA5.

FIG. 26 shows that an access point according to an embodiment of thepresent invention receives a probe request frame and a data frame from aplurality of stations, and then transmits an ACK frame for a proberesponse frame and a data frame together.

The first wireless communication terminal may transmit a response to thedata frame and a response to the management frame together.Specifically, when a plurality of second wireless communicationterminals transmit a data frame and a management frame together, thefirst wireless communication terminal may transmit a response to thedata frame and a response to the management frame together. At thispoint, the response to the data frame may be an ACK frame indicatingwhether the data frame is received or not. Specifically, the response tothe data frame may be the multi-station block ACK frame described above.

In a specific embodiment, the first wireless communication terminal maytransmit a response to the data frame and a response to the managementframe together through OFDMA. In another specific embodiment, the firstwireless communication terminal may transmit a response to the dataframe and a response to the management frame together through oneAggregate MPDU (A-MPDU). At this time, the size of at least one offrequency bands used by the response to the data frame and the responseto the management frame may be fixed. In yet another embodiment, thesize of at least one of frequency bands used by the response to the dataframe and the response to the management frame may be variable.

Further, when the trigger frame includes the same information as themanagement frame, the management frame may omit information included inthe trigger frame. Specifically, when the management frame is a proberequest frame, the probe response frame may omit information on theoperating channel since the trigger frame includes information on theoperating channel. In addition, the probe response frame may omit atleast one of information on the maximum MPDU count, information on thefrequency bandwidth, information on the guard interval, information onthe device capability such as whether STBC is supported, a time stamp,information on transmission rate, and information on the powerconstraint.

In the embodiment of FIG. 26, an access point AP transmits a triggerframe indicating a resource allocation for a random access.

The first station STA1 to the second station STA2 transmit the proberequest frame to the access point AP based on the trigger frame.

The third station STA3, the fifth station STA5, the seventh stationSTA7, and the eighth station STA8 transmit the data frame to the accesspoint AP based on the trigger frame.

The access point AP transmits a multi-station block ACK frame for aprobe response frame for the first station STA1 to the second stationSTA2 and a data frame transmitted by the third station STA3, the fifthstation STA5, the seventh station STA7, and the eighth station STA8through OFDMA.

The first wireless communication terminal may reduce the time andtransmission resources required for transmission of the response to themanagement frame through this operation.

As described above, the second wireless communication terminalunassociated with the first wireless communication terminal may transmitthe management frame to the first wireless communication terminal basedon the trigger frame. At this time, the management frame may include atleast one of a probe request frame, an association request frame, and areassociation request frame. In addition, the first wirelesscommunication terminal may use a minimum unit frequency bandwidth ormore. The minimum unit frequency bandwidth represents the smallestfrequency bandwidth that the first wireless communication terminal mayuse. In a specific embodiment, the minimum unit frequency bandwidth maybe 20 MHz.

At this time, when the first wireless communication terminal uses theminimum unit frequency bandwidth, it is a problem that which frequencyband the second wireless communication terminal unassociated with thefirst wireless communication terminal should receive the response to themanagement frame. For example, the first wireless communication terminalmay use a frequency band having a bandwidth of 80 MHz, and the secondwireless communication terminal unassociated with the first wirelesscommunication terminal may transmit the management frame through thesub-frequency band having a bandwidth of 20 MHz based on the triggerframe. At this time, the first wireless communication terminal has aproblem that which sub-frequency band of the 80 MHz bandwidth theresponse to the management frame is transmitted over. This is because,if there is no rule for a particular sub-frequency band, the secondwireless communication terminal needs to sense the entire frequencyband.

A method for transmitting a response to a management frame to a secondwireless communication terminal unassociated with a first wirelesscommunication terminal when the first wireless communication terminaluses more than the minimum unit frequency bandwidth will be describedwith reference to FIGS. 27 to 29.

FIG. 27 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits a probe response frame through aprimary channel.

When the first wireless communication terminal uses a frequency bandhaving a frequency bandwidth larger than the minimum unit frequencybandwidth, the first wireless communication terminal may transmit thesame trigger frame every minimum unit frequency bandwidth unit. In yetanother specific embodiment, the first wireless communication terminalmay transmit the trigger frame using the entire frequency bandwidth.

When the second wireless communication terminal unassociated with thefirst wireless communication terminal transmits the management frame tothe first wireless communication terminal based on the trigger frame,the first wireless communication terminal may transmit the managementframe through the predetermined sub-frequency band. At this time, thepredetermined sub-frequency band may be a primary channel. At this time,the second wireless communication terminal may acquire information onthe primary channel from the trigger frame. In another specificembodiment, the second wireless communication terminal may acquireinformation on the primary channel from the beacon frame.

Specifically, the second wireless communication terminal may transmitthe management frame to the first wireless communication terminal, andsearch for the designated sub-frequency band to which the response tothe management frame is transmitted. At this time, if the secondwireless communication terminal does not receive a response to themanagement frame for a predetermined time, the second wirelesscommunication terminal may search for the sub-frequency band thattransmits the management frame. In another specific embodiment, thesecond wireless communication terminal may transmit the management frameto the first wireless communication terminal, and search for a channelincluded in a frequency band from the designated sub-frequency band towhich the response to the management frame is transmitted.

In the embodiment of FIG. 27, the access point AP transmits the sametrigger frame in units of 20 MHz in a frequency band having an 80 MHzbandwidth. At this time, the trigger frame may indicate a frequency bandallocated for random access.

The thirteenth station STA13 unassociated with the access point APreceives the trigger frame through the fourth channel.

The eighth station STA8, the seventh station STA7, and the fifth stationSTA5 transmit the data frame to the access point AP based on the triggerframe. At this time, the thirteenth station STA13 transmits the proberequest frame through the channel that receives the trigger frame.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether a data frame transmitted by the eighth STA8, the seventh station STA7, and the fifth station STA5 is received, tothe eighth station STA8, the seventh station STAT, and the fifth stationSTA5.

The access point AP transmits the probe response frame to the thirteenthstation STA13 through the first channel, which is the primary channel.

The thirteenth station STA13 transmits an ACK frame for the proberesponse frame through the first channel, which is a primary channel.

FIG. 28 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits the same probe response frame in 20MHz frequency bandwidth units.

When the second wireless communication terminal unassociated with thefirst wireless communication terminal transmits the management frame tothe first wireless communication terminal based on the trigger frame,the first wireless communication terminal may transmit the samemanagement frame every minimum unit frequency bandwidth. At this time,the management frame may be a unicast management frame for the secondwireless communication terminal. In yet another specific embodiment, themanagement frame may be a multicast management frame or a broadcastmanagement frame for the second wireless communication terminal as wellas other wireless communication terminals. The first wirelesscommunication terminal may transmit the management frame to the wirelesscommunication terminal other than the second wireless communicationterminal through a multicast management frame or a broadcast managementframe without a separate contention procedure.

The second wireless communication terminal may transmit a response tothe management frame transmitted by the first wireless communicationterminal through the sub-frequency band in which the management frame istransmitted. At this time, the first wireless communication terminal maysearch for the sub-frequency band to which the second wirelesscommunication terminal transmits the management frame to receive theresponse to the management frame transmitted by the first wirelesscommunication terminal from the second wireless communication terminal.In another specific embodiment, when the second wireless communicationterminal does not transmit the management frame through the designatedsub-frequency band, since the first wireless communication terminal maynot know through which sub-frequency band the second wirelesscommunication terminal will transmit the management frame, the firstwireless communication terminal may search the entire frequency band.

In the embodiment of FIG. 28, the access point AP transmits the sametrigger frame in units of 20 MHz in a frequency band having an 80 MHzbandwidth.

The thirteenth station STA13 unassociated with the access point APreceives the trigger frame through the fourth channel. At this time, thetrigger frame may indicate a frequency band allocated for random access.

The eighth station STA8, the seventh station STA7, and the fifth stationSTA5 transmit the data frame to the access point AP based on the triggerframe. At this time, the thirteenth station STA13 transmits the proberequest frame through the channel that receives the trigger frame.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether a data frame transmitted by the eighth STA8, the seventh station STA7, and the fifth station STA5 is received, tothe eighth station STA8, the seventh station STA7, and the fifth stationSTA5.

The access point AP transmits the same probe response frame to thethirteenth station STA13 in units of 20 MHz in the frequency band havingthe bandwidth of 80 MHz.

The thirteenth station STA13 transmits an ACK frame for the proberesponse frame through the fourth channel transmitting the probe requestframe to the access point AP.

FIG. 29 shows that a station according to an embodiment of the presentinvention transmits a probe request frame based on a trigger frame to anaccess point using a frequency band having a frequency bandwidth of 80MHz and the access point transmits a probe response frame through theentire frequency band.

When the second wireless communication terminal unassociated with thefirst wireless communication terminal transmits the management frame tothe first wireless communication terminal based on the trigger frame,the first wireless communication terminal may transmit the managementframe through the entire frequency band used by the first wirelesscommunication terminal. At this time, the management frame may be aunicast management frame for the second wireless communication terminal.In yet another specific embodiment, the management frame may be amulticast management frame or a broadcast management frame for thesecond wireless communication terminal as well as other wirelesscommunication terminals. The first wireless communication terminal maytransmit the management frame to the wireless communication terminalother than the second wireless communication terminal through amulticast management frame or a broadcast management frame without aseparate contention procedure.

The second wireless communication terminal may acquire information onthe frequency band used by the first wireless communication terminalfrom the trigger frame. Specifically, the second wireless communicationterminal may acquire information on the channel used by the firstwireless communication terminal and information on the frequencybandwidth from the trigger frame.

In the embodiment of FIG. 29, the access point AP transmits the sametrigger frame in units of 20 MHz in a frequency band having an 80 MHzbandwidth. At this time, the trigger frame may indicate a frequency bandallocated for random access.

The thirteenth station STA13 unassociated with the access point APreceives the trigger frame through the fourth channel.

The eighth station STA8, the seventh station STA7, and the fifth stationSTA5 transmit the data frame to the access point AP based on the triggerframe. At this time, the thirteenth station STA13 transmits the proberequest frame through the channel that receives the trigger frame.

The access point AP transmits a multi-station block ACK frame Multi-STABlock ACK indicating whether a data frame transmitted by the eighth STA8, the seventh station STA7, and the fifth station STA5 is received, tothe eighth station STA8, the seventh station STA7, and the fifth stationSTA5.

The access point AP transmits the probe response frame to the thirteenthstation STA13 through the entire frequency band having the bandwidth of80 MHz.

The thirteenth station STA13 transmits an ACK frame for the proberesponse frame through the first channel, which is a primary channel.

FIG. 30 is a flowchart illustrating operations of a first wirelesscommunication terminal and a second wireless communication terminalaccording to an embodiment of the present invention.

The first wireless communication terminal 400 transmits a trigger frameindicating information on resources allocated by the first wirelesscommunication terminal 400 to the second wireless communication terminal500 (S3001). Specifically, the trigger frame may represent a resourceallocated for random access. In a specific embodiment, the trigger framemay indicate a frequency band allocated for random access through aspecific value of the AID. At this time, the specific value of the AIDmay be 0. The specific format of the trigger frame may be the same asthe embodiment described with reference to FIG. 6 to FIG. 10.

The second wireless communication terminal 500 transmits the uplink MUPPDU to the first wireless communication terminal 400 based on thetrigger frame (S3003). Not only the second wireless communicationterminal 500 associated with the first wireless communication terminal400 but also the second wireless communication terminal 500 unassociatedwith the first wireless communication terminal 400 also transmits theuplink MU PPDU based on the trigger frame. As described above, aleftover tone may be used to signal information on a management frame tothe second wireless communication terminal 500 unassociated with thefirst wireless communication terminal 400.

In addition, the first wireless communication terminal 400 may use thetemporary AID to indicate information on the second wirelesscommunication terminal 500 unassociated with the first wirelesscommunication terminal 400. At this time, the value of the temporary AIDis a value that is not allocated by association with the first wirelesscommunication terminal 400. The first wireless communication terminal400 may assign the value of the temporary AID with a value outside therange that the AID is able to be allocated. Specifically, the firstwireless communication terminal 400 may assign the value of thetemporary AID with a number other than 1 to 2007. Further, the firstwireless communication terminal 400 may designate the value of thetemporary AID based on the identifier of the second wirelesscommunication terminal 500. At this time, the identifier 500 of thesecond wireless communication terminal may be the MAC address of thesecond wireless communication terminal 500. In addition, the identifierof the second wireless communication terminal 500 may be an identifierof the second wireless communication terminal 500 used by the secondwireless communication terminal 500 when transmitting the uplink MUPPDU. Furthermore, the identifier of the second wireless communicationterminal 500 may be a value pre-known to both the first wirelesscommunication terminal 400 and the second wireless communicationterminal 500.

Specifically, the first wireless communication terminal 400 maydesignate a temporary AID value based on the following equation.Temporary AID=ID of STA % 40+2008

A specific embodiment of the second wireless communication terminal 500unassociated with the first wireless communication terminal 400 may besimilar to the embodiment described with reference to FIGS. 16 to 22.

The second wireless communication terminal 500 may transmit at least oneof the data frame, the management frame, and the BSR to the firstwireless communication terminal 400 based on the trigger frame.Specifically, the second wireless communication terminal 500 maytransmit the BSR based on a trigger frame indicating a frequency bandfor random access.

In addition, a plurality of second wireless communication terminals 500may multiplex different types of MAC frames in the frequency domainusing OFDMA transmission and transmit the MAC frames to the firstwireless communication terminal 400. For example, the data frametransmission of one of the second wireless communication terminals 500and the management frame transmission of another second wirelesscommunication terminal 500 may be multiplexed in the frequency domainthrough OFDMA.

In addition, the second wireless communication terminal 500 may transmitthe management frame to the first wireless communication terminal 400based on the trigger frame. At this time, the operation of the firstwireless communication terminal 400 and the second wirelesscommunication terminal 500 may be the same as those of the embodiment ofFIGS. 26 to 30.

There may be a plurality of MU PPDU transmissions between the firstwireless communication terminal 400 and the second wirelesscommunication terminal 500 during one TXOP. Specifically, the downlinkMPDU transmission of the first wireless communication terminal 400 andthe uplink MPDU transmission of the second wireless communicationterminal 500 may be performed in one TXOP using the trigger frame. Atthis time, the specific operations of the first wireless communicationterminal 400 and the second wireless communication terminal 500 may besimilar to the those described with reference to FIGS. 11 to 15.

As described above, the management frame may omit the informationoverlapping with the trigger frame. Specifically, the probe responseframe may omit the information overlapping the trigger frame or thebeacon frame. For example, the probe response frame may omit informationon the operating channel. In addition, the probe response frame may omitat least one of information on the maximum MPDU count, information onthe frequency bandwidth, information on the guard interval, informationon the device capability such as whether STBC is supported, a timestamp, information on transmission rate, and information on the powerconstraint.

Although the present invention is described by using wireless LANcommunication as an example, it is not limited thereto and may beapplied to other communication systems such as cellular communication.Additionally, while the method, device, and system of the presentinvention are described in relation to specific embodiments thereof,some or all of the components or operations of the present invention maybe implemented using a computer system having a general purpose hardwarearchitecture.

The features, structures, and effects described in the above embodimentsare included in at least one embodiment of the present invention and arenot necessary limited to one embodiment. Furthermore, features,structures, and effects shown in each embodiment may be combined ormodified in other embodiments by those skilled in the art. Therefore, itshould be interpreted that contents relating to such combination andmodification are included in the range of the present invention.

While the present invention is described mainly based on the aboveembodiments but is not limited thereto, it will be understood by thoseskilled in the art that various changes and modifications are madewithout departing from the spirit and scope of the present invention.For example, each component specifically shown in the embodiments may bemodified and implemented. It should be interpreted that differencesrelating to such modifications and application are included in the scopeof the present invention defined in the appended claims.

The invention claimed is:
 1. A base wireless communication terminalcommunicating with a wireless communication terminal wirelessly, thebase wireless communication terminal comprising: a transceiver; and aprocessor, wherein the processor is configured to: receive, by using thetransceiver, a medium access control (MAC) frame transmitted from thewireless communication terminal, when the wireless communicationterminal is unassociated with the base wireless communication terminal,insert an identifier for an unassociated wireless communication terminaland a MAC address of the wireless communication terminal respectivelyinto a first field and a second field of a multi-station Block ACK framewhich indicates whether at least one of MAC frames transmitted from atleast one of wireless communication terminals is received, wherein thefirst field is for indicating an association identifier corresponding toan association of each of the at least one of wireless communicationterminals with the base wireless communication terminal and the secondfield is for indicating Block ACK Bitmap, when the wirelesscommunication terminal is associated with the base wirelesscommunication terminal, insert an association identifier correspondingto an association of the wireless communication terminal with the basewireless communication terminal into the first field and set a value ofsecond field based on at least one MAC frame received from the wirelesscommunication terminal, and transmit the multi-station Block ACK frame,wherein the identifier for an unassociated wireless communicationterminal is not allocated through an association with the base wirelesscommunication terminal and not used for an associated wirelesscommunication terminal, and wherein a value of the identifier for anunassociated wireless communication terminal is out of a range of valuesthat is able to be allocated for the association identifier.
 2. The basewireless communication terminal of claim 1, wherein the value of theidentifier for an unassociated wireless communication terminal isgenerated based on the MAC address of the wireless communicationterminal.
 3. The base wireless communication terminal of claim 1,wherein the value of the identifier for an unassociated wirelesscommunication terminal is a value pre-known to both the base wirelesscommunication terminal and the wireless communication terminal.
 4. Thebase wireless communication terminal of claim 1, wherein the processoris configured to transmit a trigger frame triggering random access,wherein the MAC frame transmitted from the wireless communicationterminal is transmitted in response to the trigger frame.
 5. The basewireless communication terminal of claim 4, wherein the trigger framesignals a frequency band allocated for random access by using a value ofa specific association identifier, wherein the MAC frame transmittedfrom the wireless communication terminal is transmitted through thefrequency band allocated for random access.
 6. The base wirelesscommunication terminal of claim 5, the MAC frame transmitted from thewireless communication terminal is a management frame.
 7. A wirelesscommunication terminal communicating wirelessly with a base wirelesscommunication terminal comprising: a transceiver; and a processor,wherein the processor is configured to: receive, by using thetransceiver, a multi-station Block ACK frame which indicates whether atleast one of medium access control (MAC) frames transmitted from atleast one of wireless communication terminals is received by using afirst field of the multi-station Block ACK frame for indicating anassociation identifier corresponding to an association of each of the atleast one of wireless communication terminals and the base wirelesscommunication terminal and a second field of the multi-station Block ACKframe for indicating Block ACK Bitmap, from the base wirelesscommunication terminal, and when the wireless communication terminal isunassociated with the base wireless communication terminal and the firstfield of the multi-station Block ACK frame includes an identifier for anunassociated wireless communication terminal, determine whether a MACframe transmitted from the wireless communication terminal is receivedby the base wireless communication terminal based on whether the secondfield of the multi-station Block Ack frame includes a MAC address of thewireless communication terminal, when the wireless communicationterminal is associated with the base wireless communication terminal andthe first field of the multi-station Block ACK frame includes anassociation identifier corresponding to an association of the wirelesscommunication terminal with the base wireless communication terminal,determine whether a MAC frame transmitted from the wirelesscommunication terminal is received by the base wireless communicationterminal based on a value of bit of the second field, which iscorresponding to the MAC frame, wherein the identifier for anunassociated wireless communication terminal is not allocated through anassociation with the base wireless communication terminal and not usedfor an associated wireless communication terminal, and wherein a valueof the identifier for an unassociated wireless communication terminal isout of a range of values that is able to be allocated for theassociation identifier.
 8. The wireless communication terminal of claim7, wherein the value of the identifier for an unassociated wirelesscommunication terminal is generated based on the MAC address of thewireless communication terminal.
 9. The wireless communication terminalof claim 7, wherein the value of the identifier for an unassociatedwireless communication terminal is a value pre-known to both the basewireless communication terminal and the wireless communication terminal.10. The wireless communication terminal of claim 7, wherein theprocessor is configured to receive a trigger frame triggering randomaccess from the base wireless communication terminal, transmit the MACframe in response to the trigger frame, and determine whether the MACframe transmitted in response to the trigger frame is received by thebase wireless communication terminal based on the multi-station BlockACK frame.
 11. The wireless communication terminal of claim 10, whereinthe trigger frame signals a frequency band allocated for random accessby using a value of a specific association identifier, wherein theprocessor is configured to transmit the MAC frame through the frequencyband allocated for random access in response to the trigger frame. 12.The wireless communication terminal of claim 11, the MAC frametransmitted in response to the trigger frame is a management frame. 13.An operation method of a wireless communication terminal communicatingwith a base wireless communication terminal wirelessly and unassociatedwith the base wireless communication terminal, the method comprising:receiving a multi-station Block ACK frame which indicates whether atleast one of medium access control (MAC) frames transmitted from atleast one of wireless communication terminals is received by using afirst field of the multi-station Block ACK frame for indicating anassociation identifier corresponding to an association of each of the atleast one of wireless communication terminals and the base wirelesscommunication terminal and a second field of the multi-station Block ACKframe for indicating Block ACK Bitmap, from the base wirelesscommunication terminal, and when the wireless communication terminal isunassociated with the base wireless communication terminal and the firstfield of the multi-station Block ACK frame includes an identifier for anunassociated wireless communication terminal, determining whether a MACframe transmitted from the wireless communication terminal is receivedby the base wireless communication terminal based on whether the secondfield of the multi-station Block ACK frame includes a MAC address of thewireless communication terminal, when the wireless communicationterminal is associated with the base wireless communication terminal andthe first field of the multi-station Block ACK frame includes anassociation identifier corresponding to an association of the wirelesscommunication terminal with the base wireless communication terminal,determining whether a MAC frame transmitted from the wirelesscommunication terminal is received by the base wireless communicationterminal based on a value of bit of the second field, which iscorresponding to the MAC frame, wherein the identifier for anunassociated wireless communication terminal is not allocated through anassociation with the base wireless communication terminal and not usedfor an associated wireless communication terminal, and wherein a valueof the identifier for an unassociated wireless communication terminal isout of a range of values that is able to be allocated for theassociation identifier.
 14. The operation method of claim 13, whereinthe value of the identifier for an unassociated wireless communicationterminal is generated based on the MAC address of the wirelesscommunication terminal.
 15. The operation method of claim 13, whereinthe value of the identifier for an unassociated wireless communicationterminal is a value pre-known to both the base wireless communicationterminal and the wireless communication terminal.
 16. The operationmethod of claim 13, further comprising: a trigger frame triggeringrandom access from the base wireless communication terminal,transmitting the MAC frame in response to the rigger frame, anddetermining whether the MAC frame transmitted in response to the triggerframe is received by the base wireless communication terminal based onthe multi-station Block ACK frame.